Re: [Qemu-devel] precompiled qemu-system-x86_64 is 32 bit instead of 64bit

[Andrew Warkentin <andreww@datanet.ab.ca>]

Laurent Desnogues wrote:

>On 2/21/08, Andrew Warkentin <andreww@datanet.ab.ca> wrote:
>  
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>> Why does it matter if it is 64-bit or not? Most programs at the moment
>> don't benefit from being compiled 64-bit. I don't get the obsession with
>> 64-bitness that most Linux and BSD people seem to have.
>>    
>>
>
>I have programs that run significantly faster when targetting x86_64
>(Othello back-end solver, various prime sieves, interpreted simulator,
>MAME [cf. http://aarongiles.com/pix/benchmarks.png])., where
>significantly means >10%.  I agree I can't qualify my list as "most
>programs", but on the other hand I have yet to see one of my
>programs running slower as x86_64 bit mode (though I guess some
>programs with heavy usage of pointers could be in trouble).
>
>Did anyone compare qemu ia32 vs x86_64?
>
>
>Laurent
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>  
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I guess on x86, there is somewhat of a benefit, because of the extra 
registers. On any decent architecture, 32- and 64-bit programs would run 
at the same speed. Still, I don't think that it's worth having separate 
32- and 64-bit versions of operating systems over, even on x86.